Targeting innate immune pathways in breast cancers with chromosomal instability

项目概要/摘要 虽然在治疗原发性乳腺癌方面已经取得了相当大的进展，但转移性乳腺癌的治疗仍在继续。 主要挑战。转移性乳腺癌细胞通常具有染色体不稳定性（CIN）， 染色体水平的改变导致基因组拷贝数异常。在确定目标方面的一个主要挑战是 由CIN驱动的乳腺癌是缺乏已知的靶向改变。我们最近发现，CIN Pro- 在癌细胞中检测慢性炎症信号。当染色体错误分离时，它们往往会变成- 包裹在微核中。随后的微核破裂使基因组双链DNA暴露于 胞质液胞质DNA激活抗病毒先天免疫途径，其中主要是cGAS-STING信号- ing.在正常情况下，cGAS-STING激活促进I型干扰素并促进细胞- 介导的免疫。STING在正常上皮细胞中的参与诱导衰老和细胞死亡。我们 然而，已经表明癌细胞由于其自身的特性而对cGAS-STING活化具有内在抗性。 长期接触胞质DNA相反，它们上调STING下游的替代途径，如 作为NF-κB信号。癌细胞对慢性炎症信号的依赖程度很差， 理解。更重要的是，它们如何破坏先天免疫信号以避免免疫监视仍然存在。 未知我们正在进行的工作表明，cGAS-STING信号传导被隔离在癌细胞中，远离癌细胞。 主持人此外，人乳腺肿瘤上调ENPP 1，这是cGAS-STING信号传导的负调节因子。 ENPP 1通过降解cGAMP（cGAS产生的第二信使）使免疫逃避成为可能， 细胞外间隙因此，ENPP 1防止宿主STING响应肿瘤-宿主cGAMP活化 转移引人注目的是，STING的药理学抑制抑制了黑色素瘤的同基因模型中的转移。 乳腺癌和结肠癌。我们推测这是因为它对肿瘤细胞的抑制作用超过了它的保护作用 在主机中的作用。在这项工作的基础上，我们将扩大我们在乳腺癌中抑制STING的临床前测试- 探讨其在延迟转移和治疗抗性方面的功效（目的1）。然后我们将检查 cGAMP是否有助于免疫抑制微环境的形成， 细胞外间隙中的弯曲破裂（目标2）。最后，我们将开发基于cGAS-STING的生物标志物， 前瞻性收集肿瘤标本。我们将测试cGAS-STING信号传导的状态和 ENPP 1水平可以预测对新辅助化疗和atezolizumab（一种免疫抑制剂）的反应 最近被批准用于治疗转移性乳腺癌（Aim 3）。我们的工作解决了临床上未满足的 通过靶向患有CIN的乳腺癌的一个子集并且对于其存在有限的治疗选择来满足需要。如果 它将为首次在人体内测试STING抑制剂治疗以下疾病提供临床前依据： 癌症转移以及开发新的CIN相关生物标志物以预测治疗反应。

PROJECT SUMMARY/ABSTRACT While considerable progress has been made in treating primary breast cancers, metastatic breast cancers re- main a challenge. Metastatic breast cancer cells typically have chromosomal instability (CIN) that involves chromosome-level alterations leading to genomic copy number abnormalities. A major challenge in targeting breast cancers driven by CIN is the lack of known targetable alterations. We recently found that CIN pro- motes chronic inflammatory signaling in cancer cells. As chromosomes missegregate, they often become en- capsulated in micronuclei. Subsequent micronuclear rupture exposes genomic double-stranded DNA to the cytosol. Cytosolic DNA activates anti-viral innate immune pathways, chief among which is cGAS-STING signal- ing. Under normal circumstances, cGAS-STING activation promotes type I interferon and facilitates cell- mediated immunity. Engagement of STING in normal epithelial cells induces senescence and cell death. We have shown that cancer cells, however, are intrinsically resistant to cGAS-STING activation by virtue of their chronic exposure to cytosolic DNA. Instead, they upregulate alternative pathways downstream of STING, such as NF-κB signaling. The extent to which cancer cells depend on chronic inflammatory signaling is poorly un- derstood. More importantly, how they subvert innate immune signaling to avoid immune surveillance remains unknown. Our ongoing work reveals that cGAS-STING signaling is sequestered in cancer cells away from the host. Furthermore, human breast tumors upregulate ENPP1, a negative regulator of cGAS-STING signaling. ENPP1 enables immune evasion by degrading cGAMP, the second messenger produced by cGAS, only in the extracellular space. As such ENPP1 prevents host STING activation in response to tumor-to-host cGAMP transfer. Strikingly, pharmacologic inhibition of STING suppresses metastasis in syngeneic models of melano- ma, breast, and colon cancers. We postulate this is because its inhibition in tumor cells outweighs its protective role in the host. Building on this work, we will expand our pre-clinical testing of STING inhibition in breast can- cer probing its efficacy in delaying metastasis and therapeutic resistance (Aim 1). We will then examine whether cGAMP contributes toward the formation of an immune suppressive microenvironment through meta- bolic breakdown in the extracellular space (Aim 2). Finally, we will develop cGAS-STING-based biomarkers in prospectively collected tumor specimens. We will test whether the status of cGAS-STING signaling and ENPP1 levels can predict response to neoadjuvant chemotherapy and atezolizumab, an immunotherapeutic recently approved for the treatment of metastatic breast cancer (Aim 3). Our work addresses a clinically unmet need by targeting a subset of breast cancers with CIN and for which there are limited therapeutic options. If successful it will provide pre-clinical rationale for first-in-human testing of STING inhibitors for the treatment of cancer metastasis as well as the development of novel CIN-related biomarkers to predict therapeutic response.